Refrigerating apparatus



Nov. 26, 1940. J. L. FLETCHER 2,222,707

REFRIGERATING APPARATUS Filed Nov. so, 1958 Fig.1.

58 as M H Inventor:

James L.Tletohen H is Attorney Patented Nov. 26, 1940 UNITED STATES REFRIGERATING APPARATUS James L. Fletcher, Sche to General Electric Co New York nectady, N. Y., assignor mpany, a corporation of Application November 30, 1938, Serial No. 243,156

9 Claims.

This invention relates to refrigerating systems and more particularly to refrigerating systems including a plurality of evaporators operable at different temperatures.

It is an object of my invention to provide simple, efiicient and reliable apparatus to control the operation of refrigerating systems of the above-mentioned type.

It is a further object of my invention to provide improved apparatus for controlling the operation of refrigerating systems of the above type according to the pressures existing in said systems.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of my invention reference may be had to the accompanying drawing in which Fig. 1 illustrates schematically a system embodying the principles of my in- Vention; and Fig. 2 is a side elevation, 'partly in section, of a valve for use in the system illustrated in Fig. 1.

In the system disclosed by Fig. 1, I have shown a high temperature evaporator I and a low temperature evaporator II having a compressor I2 and condenser I3 common thereto. In a refrigcrating system including high and low temperature evaporators with a common compressor and condenser it is necessary to provide means to connect the evaporators to the compressor in 35 such a manner as to maintain a pressure differential between the evaporators. For this purpose, I provide a differential valve I4 which connects selectively either evaporator III or evaporator II to the suction line I5 according to the 40 difference of pressures in evaporators I 0 and II.

Referring to Figs. 1 and 2 in greater detail, refrigerant vapor is compressed in compressor I2 and discharged into condenser I3 by way of conduit I6. Liquified refrigerant flows from con-' denser I3 into float valve I1 by way of a conduit I8. Evaporator I0 is supplied with refrigerant from float valve I'I byway of conduit I9.

Evaporators I0 and II may be of any desired form although I have illustrated my invention in connection with two flooded type evaporators. The evaporators Ill and II may be operated at any two desired temperatures. For example, one may be maintained below the freezing temperature in order to freeze ice, frozen desserts, etc., and also to maintain articles in a frozen state while the other evaporator may be usedfor the preservation of foods. I have illustrated evaporator II] as having two headers 20 connected by a conduit 2 I. Liquid refrigerant is supplied to low temperature evaporator II from headers 20 by 5 means of a float valve 22 and conduits 23 and 24.

It will be obvious that liquid refrigerant will pass into float valve 22 only when the liquid refrigerant level in headers 20 is sufiiciently high to overflow through conduit 23. Valve I4 communicates with header 2!] of evaporator I0 above the liquid level therein by means of an inlet conduit 25. Valve I 4 communicates With header 26 of low temperature evaporator II above the liquid level therein by means of a second inlet conduit 21. Valve I4, as will be described later, connects either conduit 25 or conduit 21 to suction line I5 in order that the vaporized refrigerant in header or 26, respectively, may be drawn into compressor I2.

As shown in Fig. 2, valve I4 comprises a casing or chamber 28 having end walls 29 and 30. Chamber 28 may be incorporated in the casing of compressor I2 or separate therefrom as illustrated. An inlet tube 3| extends through end Wall 29 into the interior of casing 28 through a suitable opening and is secured to end wall 29 in any desirable manner, as by welding, thereby providing for the reception of vaporized refrigerant drawn from header 2B of evaporator II 30 through conduit 21. Tube 3| is provided with one or more ports 32 intermediate the inner end of tube 3| and the end wall 29. In a similar manner I have provided a second inlet tube 33 extending through the opposite end wall 30 for 35 receiving vaporized refrigerant from header 20 through conduit 25. Tube 33 is provided with one or more ports 34 arranged similarly to ports 32.

In order to provide communication between 40 the interior of casing 28 and one of the evaporators Iprovidea piston or plunger 35 which is ar ranged to reciprocate in tubes 3I and 33. Plunger 35 is dimensioned so that one set of ports is closed while the other set of ports is uncovered so that the associated inlet conduit is put into communication with the interior of casing 28 and. also dimensioned so that during a portion of time plunger 35 is moving from one selective position to another, both ports 32 and 34' will be closed.- For example, as indicated in Fig. 2, ports 32 will be closed before ports 34 are uncovered, assum ing that plunger 35 is moved to the right. Thus,

as the plunger 35 moves from one selective position to another selective position, at some predeably of resilient material is connected to the lastmentioned end of bellows 36. The other end of arms 31 is suitably shaped to rest within recess 38 or recess 39 provided in an extension 40 of the second inlet tube 33. The operation of this device will be described later. The positions of recesses 38 and 39 serve to determine the amount of travel of piston 35. v

In order tofobtain and preserve the necessary difierence of pressures between the evaporators i0 and II I have provided a spring 4| between bellows 36 and end wall 29 tending to bias the plunger 35 toward the left as viewed in Fig. 2. Ann 31 and extension 40 cooperate with spring 4| to provide the pressure differential as will be apparent when the operation of the valve I4 is described.

Inasmuch as bellows 36 divides valve l4 into two compartments 42 and 43, respectively, I have provided suction line i5 with branches 44 and 45 communicating with compartments 42 and 43 respectively,through suitable openings in casing 28 and secured to casing 28 in any suitable fashion as by welding.

The operation of valve l4 in the system illustrated in Fig. 1 will now be described. If it be assumed that the pressure in low temperature evaporator plus the force biasing the plunger toward the left, as viewed in Fig. 2, is greater than the pressure in high temperature evaporator ID, the plunger 35 will be as shown in Fig. 2. In this position, vaporized refrigerant will pass from header 26 of low temperature evaporator through conduit 21 into inlet chamber or tube 3| from whence the vaporized refrigerant will pass through ports 32 into compartment 43 and finally through branch conduit 45 into suction line l5. The connection between evaporator Hi and suction line I5 is, ,of course, closed by means of plunger 35. When the pressure relations in evaporators l0 and II respectively, change to such a degree that the pressure exerted on the left hand end of plunger 35 becomes greater than the bias force and pressure in the low temperature evaporator plunger 35 will be urged to:- ward the right. Inspection of Fig. 2 will show that this movement will be prevented as long as arms 31 rest in recesses 33'but it will be clear that when the pressure urging plunger 35 toward the right is sufiiciently great, arms 31 will be forced out of the recesses 38 whereupon plunger 35 will move toward the right until arms 31 fall into recesses 39. It will now be clear that the arrangement of arm 31 and recesses 33' gives a snap action such that when the pressure diiierential is large enough to pull arms 31 out of the recesses 33 the plunger 35 will immediately jump to its alternative position, thereby closing ports 32 and uncovering ports 34. In this position, conduit 25 and therefore evaporator II will be put into communication with suction line i5 through inlet chamber or tube 33, ports 34, chamber 42 and branch conduit 44.

From what has already been said, it will be clear that the differential between the pressures in evaporators l0 and II will depend upon the recesses affects the differential because the deeper the recess or the further arm 31 is permitted to drop into the extension 40 the more pressure will be required to lift arms 3] outof the recesses.

While my invention is described in connection with a particular device, modifications will be apparent to those skilled in the art.

I have provided a temperature control for the above described system. As illustrated in Fig. 1, operation of compressor l2 and its driving motor 50 from a suitable source of power supply 55 is controlled by means of ,a switch-5| actuated by a bellows 52. Bellows 52 is connected through a conduit 53 with thermostatic bulb 54 which is arranged in good heat exchange relationship with high temperature evaporator I0. Whenever the temperature of evaporator l0 exceeds the value for which the control bellows 52 is adjusted, the thermostatic fluid in bulb 54 will expand into conduit 53 and bellows 52 causing the latter to elongate and operate switch 5|, thereby energizing motor 50 from electric supply lines 55 tooperate compressor 2. When the temperature of evaporator I0 is sufliciently lowered, the pressure in bellows 52 will decrease, permitting contraction of bellows 52 and opening of switch 5| to halt operation of motor 50 and compressor l2.

While I have shown aparticular embodiment of my invention in connection with a compression machine, I do not desire my invention to be limited to the particular construction shown and described and I intend in the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a refrigerating system, a plurality of evaporators adapted to operate at difi'erent temperatures, means for withdrawing vaporized refrigerant from said evaporators, and a single pressure responsive means associated with said evaporators, said means being directly responsive to the difference of pressures between said evaporators for selectively connecting one of said evaporators to said withdrawing means.

2. In a refrigerating system, a plurality of evaporators adapted to operate at different temperatures, means for withdrawing vaporized refrigerant from said evaporators and a single pressure responsive means associated with said .means being arranged for cutting ofi communication between said plurality of evaporators at a predetermined point during the movement of said means from one selective position to another selective position.

3. In a refrigerating system having a plurality of evaporators adapted to operate at diflerent temperatures, means including a chamber for withdrawing vaporized refrigerant from said evaporators, means providing communication between said chamber and one of said evaporators, additional means providing communication between said chamber and another of said evaporators, and a single pressure responsive means associated with said evaporators, said means being directly responsive to the dlflerence of pressures between said evaporators for selectively closing one and opening the other of said communication means or opening said one and closing said other of said communication means.

4. In a refrigerating system, a plurality of peratures, means including a chamber for withdrawing ":aporized refrigerant from said evaporators, means providing communication between said chamber and one of said evaporators, ad- 10 ditional means providing communication between said chamber and'another'of said evaporators, and a single pressure responsive means associated with said evaporators, said means being directly responsive to the difierence in pressures between said evaporators for selectively closing one and opening the other of said communication means or opening said one and closing said other of said communication means, said last-mentioned means being arranged to close the open communication means before opening the closed communication means.

5. In a refrigerating system, a plurality of evaporators adapted to operate at different temperatures, means including a chamber for withdrawing vaporized refrigerant from said evaporators, means providing communication between said chamber and one of said evaporators, additional means providing communication between said chamber and another of said evaporators, a single pressure responsive means associated with said evaporators, said means being directly responsive to the difference in pressures between said evaporators for selectively closing one and opening the other of said communication means or opening said one and closing said other of said communication means, said lastmentioned means being arranged to close the open communication means before opening the closed communication means, and means for ob- 40 taining snap action of said pressure responsive means.

6. In a refrigerating system having a plurality of evaporators adapted to be operated at different temperatures, means for withdrawing vapor- 45 ized refrigerant from said evaporators, means directly responsive to the difference of pressures between said evaporators for selectively providing communication between one of said evaporators and said withdrawing means, said pressure 50 responsive means including a chamber, a first inlet conduit communicating between said chamber and one of said evaporators, a second inlet conduit communicating between said chamber and another of said evaporators, each of said 55 conduits communicating with the interior of said casing, and a plunger arranged for selectively closing one or the other of said inlet conduits.

7. In a refrigerating system having two evaporators adapted to be operated at difierent tem- 60 peratures, means for withdrawing vaporized refrigerant from said evaporators; means directly.

responsive to the difierence of pressures between evaporators adapted to operate at different tem said evaporators for selectively providing communication between one of said evaporators and said withdrawing means, said means including a casing, a first inlet conduit communicating between said casing and one of said evaporators and extending into said casing, a second inlet conduit communicating between said casing and the other of said evaporators and extending into said casing, each of said conduits having a port communicating with the interior of said casing, and a plunger arranged to reciprocate in both of said conduits for selectively closing said port in one or the other of said inlet conduits, said plunger being so arranged as to close the open port before opening the closed port.

8. In a refrigerating system having two evaporators adapted to be operated at different'temperatures, means including a compressor and a chamber for withdrawing vaporized refrigerant from said evaporators, means directly responsive to the difference of pressure between said evaporators for selectively connecting one or the other of said evaporators to said compressor, meansincluding a first-inlet conduit for providing communication with one of said evaporators and said chamber, additional means including a second inlet conduit communicating between the other of said evaporators and said chamber, one of said inlet conduits having a plurality of spaced apart recesses, a piston adapted to reciprocate in both of said inlet conduits, and means including a resilient member having one end thereof associated with 'said piston for obtaining snap action of said piston, the other end of said member being arranged to rest in one of said recesses.

9. In a refrigerating system having two evaporators adapted to operate at difierent temperatures, a compressor common to both, valve means directly responsive to the difference of pressures between said evaporators for selectively connecting one or the other of said evaporators to said compressor, a casing, a first inlet conduit com municating with one of said evaporators and extending into said casing, a second inlet conduit -communicating with the other of said evaporators and extending into said casing, a suction line communicating between said compressor and said casing, a port in each of said inlet conduits, a piston adapted to reciprocate in both of said inlet conduits for selectively closing one or the other of said ports, a bellows, one end of said bellows being attached to said casing, the other end of said bellows being attached to said piston intermediate the ends thereof, means including a spring arranged to bias said piston in one direction, one of said inlet conduits having two spaced-apart recesses, a resilient member having one end thereof attached to said bellows, the other end of said member being arranged to rest inone or the other of said recesses.

JAMES L. FLETCHER. 

